JPS62181127A - Preparation of metal-clad laminated sheet - Google Patents

Abstract

PURPOSE:To produce by only one process a laminated sheet adhered tightly, with no foam between the layers and with a superior high-frequency property, by overlaying a heat resistant thermoplastic resin film and a metal foil on a metallic core plate and by adhering them under heating and reduced pressure. CONSTITUTION:A heat resistant thermoplastic resin film and a metal foil are overlaid on a metallic core plate whose surface is roughened, and are adhered under heating and reduced pressure atmosphere. By this operation, a metal-clad laminated layer with a superior high-frequency property and with little foam remaining between the layers and being suitable as the material of a metallic core printed-wiring board can be obtained. If the heat adhering is carried out under normal pressure, some foam remains between layers or in a penetration pit of the core plate. In case of the heat adhering under the atmosphere of reduced pressure of about 600mmHg, little foam is obviously recognized. The temp. of the heat adhering is in the range of 200 deg.C-450 deg.C. In case of the temp. being lower than 200 deg.C, adhesion strength between the core plate and the film is weakened and higher than 450 deg.C, the film is deteriorated. Adhesion pressure in the range of 1-200kg/cm<3> is recommended. When the pressure is less than 1kg/cm<3>, foams cannot be sufficiently eliminated and above 200kg/cm<3>, dimensional resistance becomes worse.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for obtaining a metal foil-clad laminate suitable as a material for a metal-core printed wiring board.

(Prior art) A metal core printed wiring board consists of a metal core plate and a conductive circuit layer provided on its surface with an insulating layer interposed in between, and has excellent heat dissipation and magnetic shielding properties, and is used for hybrid RC boards, etc. It is used for various purposes.

Conventionally, four types of laminates, which are the raw materials for metal-core printed wiring boards, have been made by thermo-compression bonding epoxy resin-impregnated glass l1iIIIi mat (glass epoxy) and copper foil to a metal core plate.

(Problems to be Solved by the Invention) However, the Ml plate whose core plate is coated with glass epoxy does not have sufficient high frequency characteristics, and there has been a desire for one with even higher performance.

This 8 again! [Layered plates had the disadvantage of trapping air bubbles between the layers during manufacture.

(Means for Solving the Problems) The present invention has a heat-resistant thermoplastic resin film and a metal foil layered on a metal core plate and bonded by thermocompression in a reduced pressure atmosphere.
We succeeded in obtaining a laminate with excellent high frequency characteristics and extremely few air bubbles remaining between the layers.

The present invention will be explained in detail below.

The metal core plate used in the present invention may be a flat plate or may have a large number of through holes provided in advance, and usually has a diameter of 0°1 to 1.6 m.
The thickness is about m. Materials include iron, aluminum, copper,
There are zinc, etc.

This core plate is one whose surface has been finely roughened by roughening treatment such as sand blasting, liquid honing, and etching. This is thought to be because the roughened surface makes it easier for living room air to escape during thermal bonding, and the anchoring effect of the roughened surface combines to increase adhesive strength, making it difficult to obtain sufficient adhesive strength with a smooth board.

The degree of surface roughening varies depending on the type of core plate and resin used in the V4 layer, but it is generally determined by the center line average roughness Ra (JIS
It is preferable that BO601) be 0.1 μI11 or more. There is no particular upper limit to the roughness as long as it does not damage the surface condition of the resulting laminate, but it is usually 10μ.
I11 or less is sufficient.

For example, in a case where the core plate is made of a copper plate in order to use the core plate as a conductor, sodium persulfate treatment l11j
By etching the surface of the copper plate, Ra of the surface of the copper plate may be set to 0.1 μm or more, preferably 0.5 μ1 or more.

The heat-resistant thermoplastic resin film includes thermoplastic resins that are resistant to soldering heat, such as polysulfone, polyneedleetherketone, polyphenylene sulfide, thermoplastic fluororesin, polyetherimide, polyethernalfon, polyamideimide, etc. films can be used, and all of these have better high frequency properties than glass epoxy.

For example, the high-frequency characteristics of glass epoxy at 1M l-1z have a dielectric constant ε of 4.5 to 5. O, dielectric loss tangent tan
While δ is said to be 0.018 to 0.022, the above resin has an ε of 3.0 to 3.8 and a tan δ of 0.000.
It can be seen that the value is as small as about 5 to 0.01, and the high frequency characteristics are excellent.

These resin films can also be filled with glass fibers or inorganic particles to further improve heat resistance.

The thickness of the film is preferably about 0.025 to 0.3 mm.

As the metal foil for forming the conductive circuit, ordinary electrolytic copper foil or the like can be used.

To laminate the core plate, film, and metal foil, stack them in this order and heat-press them under reduced pressure □.

The degree of reduced pressure (difference between normal pressure and residual pressure) is 60Qmm) 1g or more, preferably 650mn+t-1o or more. If the degree of pressure reduction is lower than this, the air bubbles will not be completely removed.

When thermocompression bonding is performed under normal pressure, air bubbles remain between layers and in the through holes of the core plate, and these air bubbles are easily removed even when high temperature and pressure are applied.
Not only is the film not completely removed, but the severe heat-pressing conditions cause the film to flow out and cause thermal deterioration. However, when thermocompression bonding is carried out under reduced pressure conditions of 600 mm HtJ and degrees, almost no noticeable air bubbles are observed.・□Here・The thermocompression bonding temperature is the resin strength that makes up the film;
The temperature must be within the range below the thermal decomposition temperature.C Naturally, this will vary depending on the material of the film, but in general, below 200°C, the adhesive strength between the core plate and the film is weak, and above 450°C, the film will deteriorate. It is necessary to keep the temperature within the range of 200 to 450 degrees Celsius because the temperature may deteriorate or flow and reduce the thickness significantly.

Also, the crimping pressure is 1 to 200 kO/CI+1 in gauge pressure.
2. In particular, the range of 10 to 100 kg/'cm2 is good,
If it is less than 1 kg and 7 cm2, air bubbles between layers and holes will not be removed sufficiently even under reduced pressure, and the adhesive strength will be weak.
If Qkg exceeds 7cm2, the ViJI body is likely to warp or twist, resulting in poor dimensional stability. Practically 5Q
Sufficient adhesive strength can be obtained with a pressure of about kg7cIl12.

When thermocompression bonding is completed, cooling begins. This cold.

Although it is preferable to pressurize during cooling, it is not always necessary to maintain reduced pressure. : The film and metal foil layer may be provided on one side of the core plate, or may be provided on both sides.

(Example 1) A 20 cm square copper plate with a thickness of 0.8 mm was treated with IIf2 oil, washed with water, and then surface treated with sodium persulfate, followed by a heat-resistant thermoplastic resin film with a thickness of 250 μm. Layer copper foil of 35μ01, pressure reduction degree 700mn+t
-Thermocompression bonding was carried out under a reduced pressure of -1 g.

a) Polysulfone (filled with glass fiber) 1)) Polyether sulfone C) Polyneedleimide d) Polyphenylene sulfide (filled with glass fiber) For thermocompression bonding, a concave lower mold and a single arrow that was almost airtightly aligned with the lower mold were used. The laminate was sandwiched between a convex upper mold and the gap between the lower mold and the upper mold was depressurized using a vacuum pump. The pressure bonding conditions were a pressure of 50 kg/C12, and after reaching the temperature shown in Table 1, the temperature was maintained for 10 minutes.

Obtained fl! The adhesive force between the copper plate and the film was measured in accordance with JIS C6481 for the single layer body. The results are shown in Table 1.

Although no air bubbles remained between the layers in any of the laminates in Table 1, sufficient adhesive strength could not be obtained with NO6 using a smooth plate as the core plate.

For comparison, microscopic observation of the cross section of a laminate made of polyetherimide film thermocompressed at a temperature of 280 to 380'C under normal pressure revealed a diameter of 10
A large number of bubbles with a size of 1 μm or more were observed, and a laminate that was difficult to put into practical use was obtained.

(Effects of the Invention) According to the present invention, a heat-resistant thermoplastic resin film and a metal foil are superimposed on a roughened metal core plate, and the vacuum strips (f) are thermocompressed at T=, resulting in excellent high-frequency characteristics. , it is possible to obtain a laminate in which the layers are firmly bonded without containing air bubbles in one step.

Claims (1)

[Claims] A heat-resistant thermoplastic resin film is layered on a metal core plate with a roughened surface, and a metal foil is layered on top of that to reduce the pressure to 6.
Under a reduced pressure atmosphere of 00 mmHg or more, at a temperature of 200
A method for manufacturing a metal foil-clad laminate having a metal core, characterized by thermocompression bonding under conditions of ~450°C and a pressure of 1~200 kg/cm^2.